Silicon carbide semiconductor device and process for producing the same

Abstract

A method for fabricating a semiconductor device includes the steps of implanting ions into a silicon carbide thin film ( 2 ) formed on a silicon carbide substrate ( 1 ), heating the silicon carbide substrate in a reduced pressure atmosphere to form a carbon layer ( 5 ) on the surface of the silicon carbide substrate, and performing activation annealing with respect to the silicon carbide substrate in an atmosphere under a pressure higher than in the step of forming the carbon layer ( 5 ) and at a temperature higher than in the step of forming the carbon layer ( 5 ).

1. A method for fabricating a silicon carbide semiconductor device, the method comprising the steps of:
 (a) implanting impurity ions into a silicon carbide layer; 
 (b) heating the silicon carbide layer under a pressure condition lower than an atmospheric pressure to form a carbon layer on a surface of the silicon carbide layer; and 
 (c) after the step (b), performing an activation annealing process with respect to the silicon carbide layer in an atmosphere at a temperature higher than in the step (b) and under a pressure condition higher than in the step (b). 
 
     
     
       2. The method of  claim 1 , wherein the steps (b) and (c) are performed in the same heating furnace. 
     
     
       3. The method of  claim 1 , wherein the step (b) includes forming the carbon layer in the presence of a gas containing hydrogen. 
     
     
       4. The method of  claim 1 , wherein the step (b) includes forming the carbon layer under a pressure condition not lower than 1×10 −5  Pa and not higher than 10 Pa. 
     
     
       5. The method of  claim 1 , wherein a temperature of the silicon carbide layer is not lower than 1100° C. and not higher than 1400° C. in the step (b). 
     
     
       6. The method of  claim 1 , wherein the step (c) includes performing the activation annealing process by adjusting a temperature of the silicon carbide layer to a range not lower than 1500° C. and not higher than 2000° C. under a pressure condition not lower than 1 kPa and not higher than 100 kPa. 
     
     
       7. The method of  claim 1 , further comprising the step of:
 (d) after the step (c), heating the silicon carbide layer in the presence of a gas containing oxygen atoms to remove the carbon layer. 
 
     
     
       8. The method of  claim 7 , wherein a temperature of the silicon carbide layer is not lower than 500° C. and not higher than 1000° C. in the step (d). 
     
     
       9. The method of  claim 7 , wherein the removal of the carbon layer in the step (d) is performed in the same heating furnace as the activation annealing process in the step (c).